Halomethyl-4-halobenzanthrones



Patented Nov. 28, 1950 UNITED STATES PATENT OFFICE HALOMETHYL-4-HALOBENZANTHRONES David I. Randall and Saul R. Buc, Easton, Pa.,

assignors to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application April 30, 1949, Serial N0. 90,774

6 Claims. (Cl. 260-364) :ent No. 787,175 for preparing bromomethylbenzanthrone by the action of bromine on 2, 5, or 6- methylbenzanthrone. The starting materials for this halomethylbenzanthrone are difficult to prepare and moreover lack any great utility in the dyestufi art.

It has now been found that 4-bromoand 4- chlorobenzanthrone can be halomethylated with almost quantitative yields of the 9-halomethyl- 4-halobenzanthrone derivative in a simple and novel manner. It is surprising that 4-halobenzanthrone can be halomethylated in a simple manner and with high'yields in view of the fact that benzanthrone has not been previously chloromethylated.

In our new process 4-halobenzanthrone of the formula I Hal (Hal-:Br or Cl) is dissolved in a solvent for the reactants such as 96% sulfuric acid. Dihalodimethyl ether is reacted with the halobenzanthrone at an elevated temperature in the range of 30 C. to 80 C. and preferably about 60 C. i

solvent such as chlorobenzene. The product which is obtained in yields of over 99% has the formula Hal (Hnl=Br or Cl) The preferred solvent for the reactants is the concentrated sulfuric acid since it is inexpensive, catalyzes the reaction and dissolves readily .the two reactants, 4-halobenzanthrone and di- Example 30.9 g. of 4-bromobenzanthrone, of theoretical bromine content, was dissolved in 230.0 cc. of

96% sulfuric acid at 30 C. To this solution 17.6

A violet red solution is obtained which is poured I into ice and water, thus precipitating a, bright 70 C. It is then crystallized from an organic cc. of dichlorodimethylether, B. P. 104 C., was added dropwise in 35 minutes. The temperature was increased to C. and held for 16 hours. The violet rod solution was poured into ice and water and the precipitated bright yellow solid was removed by filtrationf The moist solid was washed free of acid and dried at C. By this method 35.5 g. were obtained, which represents over 99% yield, M. P, -189, after crystallizing from chlorobenzene theM. P.- was 204-206.

Halogen analysis gave Br 22.2, calc. 22.1; Cl 10.0, calc. 9.9.

In another run six times as large as the above 213.0 g. of product were obtained. The entire amount was dissolved in 2130 g. of chlorobenzene. -A small quantity of tar remained and was removed by filtration; it amounted to 6.0 g. The clear yellow solution was chilled to 15 C. and stirred at this temperature for several hours.

The yellow precipitate which formed was filtered off and weighed 164.0 g., M. P. 20l-202 C. Removal of the solvent chlorobenzene from the filtrate gave 41.8 g. of a yellow compound of M. P. 169-180. It possessed the same properties as the higher melting fraction and by analysis its empirical formula was adduced the same as the compound melting at 201202 C.

The reaction involved may be represented by the following structural equation:

CHzCl The 9-chloromethyl-4-bromobenzanthrone may be employed as anintermediate in the production of vat dyes by condensation directly with amino anthraquinones ,or by first reacting the".

with stirring. ,The ;.yellow r compound .which :is

precipitated is filtered; :washed with acetone-and dried. .The yield is;22.5;g. The .productjis soluble .in .water with=a ;s1ight greeni$h fluorescence and ;is decomposed readily .by warming :in 1 aqueous zbase. Itisa-goodgermicide.

As indicated by the twoxmeltingipointsigiven in the example the product of the reaction may be a mixture. It may be'that the chloromethyl :groups L on some 'molecules -may 'be in .positions 'other than the e-position and as such the new compounds-of this invention may-'be indicated generally as Lemma! .'Having now :particularly described our invenstion and set forth the best manner ofperforming :1t;what we claim as'new is:

In the case of the 1. A halomethyl--halobenzanthrone having the formula:

-wherein Hal is amember of the group consisting v.of.,chlorine :and bromine.

{A.Q-halomethyl--halobenzanthrone having .the; formula CHzHal wherein =H-al'is'a memberi of .the; group .consistin of "chlorine and bromine.

3. The .-i9chloromethyl-4abromobenzanthrone shaving theformula:

4. The process of producing a 9-halomethyla4- halobenzanthrone which,.comprises reacting a 4- halobenzanthrone having the formula:

"wherein Hal represents.v a member of the group consisting, of; chlorine and bromine witha dihalo- 'dimethyl ether havingitheformula wherein' l-lal 'hasthesame meaning'as-abovaatia temperature of from 30-C.='to 80 Cgin'a. solvent for the reactants.

-5. The process of-'pro'ducing"9-chloromethy1 4=-- bromobenzanthrone which comprises reacting 4- bromobenzanthrone having the formula:

with dichlorodimethyl ether having the formula at a temperature of from C. to 80 C. in a concentrated sulfuric acid solution.

6. The process of producing 9-ch1oromethyl-4- bromobenzanthrone which comprises reacting 4- vbromo-benzanthrone with dichlorodimethyl ether at a temperature of C. in a concentrated sulfuric acid solution and. recovering the product by pouring into ice Water and filtering.

DAVID I. RANDALL. SAUL R. BUC.

No references cited. 

1. A HALOMETHYL-4-HALOBENZANTHRONE HAVING THE FORMULA: 